RU2527811C2 - Valve unit - Google Patents

Abstract

FIELD: machine building.

SUBSTANCE: unit is intended for flow regulation in hydraulic-circuit systems. The unit comprises the high-pressure and low pressure connection, one connection of the motor bore, flow regulation valve, located between the high pressure connection and the motor bore connection and which comprises a flow opening, capable to regulate between a fully closed and fully open positions, and the pressure regulator, located between the high pressure connection and flow regulation valve, in which the regulator pressure, acting in the first connection point between the pressure regulator and flow regulation valve, acts on a pressure regulator through the first pilot passage to close it, the second pilot passage comprising the first stop capable to shift the load pressure, acting in the motor bore connection, from the second connection point, located between the flow regulation valve and motor bore connection, through the first stop to the third connection point, the first pilot pressure acts, and the third connection point is connected to the pressure regulator to act on it towards the opening by means of the named first pilot pressure, where the third connection point is connected to the low pressure connection through the adjustable second stop.

EFFECT: higher reliability.

7 cl, 8 dwg

Description

The invention relates to a valve device, and in particular to a valve device for use in a hydraulic system.

Hydraulic systems are used on various types of moving installations to control the operation of tools and the functions of moving installations. Basically, there are two different types of valves for hydraulically controlling such tools or functions: open center valves and load sensing valves, which are commonly referred to as LS valves.

Open center distributors are mainly used in systems that include a constant displacement pump. The pump creates a constant flow and is often driven by a diesel engine with a given constant speed. When the valve that controls the tool is in the middle position, the hydraulic fluid flows at low pressure through the "open center" of the valve back into the reservoir. If the distributor is adjusted to deliver the flow to the function, this will entail a simultaneous decrease in the flow through the open center to an appropriate level. The pump pressure used in open center valves depends on the load that must be overcome in order to perform the required action.

LS valves, on the other hand, are mainly used in systems with variable displacement pumps. The pump capacity is continuously controlled by the valve system, so that the flows of the required size achieve various functions. Alternatively, the variable displacement pump can be replaced with a constant displacement pump and the so-called bypass valve for measuring the load. Such a system requires less initial investment, but higher operating costs due to greater energy losses. The invention is mainly intended for use in LS systems.

BACKGROUND OF THE INVENTION

Figure 1 shows a traditional LS valve, which is equipped with a pressure regulator R. A pressure regulator is typically used in hydraulic systems to which pump P delivers flow to achieve better control of all functions. The first pressure P _OC acts through the first control channel on the first side of the pressure regulator R. The second pressure P _L acts on the other side of the pressure regulator R and corresponds to the pressure in the bore of the working tool motor to which the pump P is connected. The spring S is configured to act on the same side of the pressure regulator (lower side in figure 1), in which the force springs can be considered appropriate pressure ΔP. Therefore, the pressure drop across the manifold or flow control valve F will always be ΔP.

This operation means that for a certain position of the lever control, the flow through the distributor will also be significant, regardless of the load. A conventional load sensing valve delivers flow to a consumer that is proportional to the size of the orifice of the flow control valve F at any given time. This flow is delivered even if the consumer cannot receive the flow, which occurs when the load has high inertia. In this case, the change in the load speed takes a relatively long time. If the valve delivers a flow in excess of the flow that the load hole is able to receive, the pressure will increase, and, ideally, the pressure will increase simultaneously, that is, very quickly. In practice, the pressure rises until the pressure relief valve (not shown) opens and limits the pressure to the predetermined highest value. A rapidly rising pressure accelerates the load as much as possible, so that the load speed increases. An ideal load measurement system is not suitable for high inertia loads or for functions in which pressure rather than flow is preferred. The regulation of inertial loads by means of a load measuring valve means that the regulation becomes spasmodic, since acceleration is either absent or maximum.

US 4,981,159 describes an LS valve with a pressure compensator, in which a pressure regulator is used to continuously control the pressure difference in another way.

The pressure difference is the difference between two pressures that act on opposite areas in which one of the areas is subject to the additional force exerted by the spring S. Therefore, in principle, the pressure difference corresponds to the force of the spring converted to pressure, i.e. ΔP. The fact that the pressure regulator R is adjusted in such a way that essentially a constant pressure difference arises independently of the flow through the valve can then be used in various ways, for example, to provide flow control.

In the conventional LS valve, which is shown in FIG. 1, this feature of the pressure regulator R is used to provide a constant pressure drop across the inlet restrictor of the flow control valve. Instead, in the solution of US Pat. No. 4,981,159, which is schematically shown in FIG. 2, this feature is used to provide a constant flow through the restrictor 38. The restrictor 38 is usually very small compared to the restrictor of the flow control valve F by a value of the order of several percent. Therefore, the controlled flow in FIG. 2 is substantially less than the largest controlled flow in FIG. 1.

The adjustable flow in FIG. 1 is used to provide precise control of the load rate attached to the valve. Instead, the substantially lower flow in FIG. 2 is used to control the pressure of the pressure regulator by controlling the size of the restrictor 44 by means of lever control by the operator.

When the lever control of the valve is in the middle position, the stop 44 is maximally open. A constant flow through the restrictor 38 can then pass through the variable restrictor 44 with a small pressure drop. Therefore, the pressure signal on the pressure regulator R corresponds to a low pressure. Therefore, the pressure regulator R must adjust its output pressure to a pressure that corresponds to the pressure of the spring force. This pressure usually ranges from 5 to 10 bar. When the operator manipulates the valve, the variable stop 44 will continuously close depending on the position of the lever. Consequently, a constant flow through the restrictor 38 will meet more resistance as it passes through the restrictor 44 to the reservoir T, and therefore the pressure P _S in the signal channel will increase. Accordingly, the regulated pressure of the pressure regulator will increase. The adjustable pressure will become equal to P _S plus pressure ΔP, which corresponds to the force of the spring. Therefore, in principle, the regulated pressure will be completely independent of the flow that passes through the inlet restrictor to the load.

A relatively minor change in figure 2 relative to figure 1 means that the flow control valve has received completely opposite properties. Instead of controlling the flow to the load, the control has changed diametrically opposite, so that instead the pressure is controlled closer along the intake restrictor.

Both different valve devices are preferred under certain, but different conditions, and substantially less preferred under other conditions. Therefore, it is of interest to combine these properties depending on actual conditions.

US 7 353 749 describes a system in which in principle it is possible to switch between two systems depending on the actual conditions. However, the system is relatively complex and does not provide a completely satisfactory solution.

Therefore, there is a need for a valve device having a relatively simple design and providing flexible control of the hydraulic system depending on actual conditions.

SUMMARY OF THE INVENTION

The objective of the invention is to provide a valve device with a relatively small number of components included in its composition, providing flexible flow control in a hydraulic system. This problem is solved by means of a valve device according to paragraph 1.

The invention relates to a hydraulic valve device including a high pressure connection and a low pressure connection; at least one connection of the hole of the motor, which is configured to connect to the hole of the motor on a hydraulic motor, preferably a hydraulic cylinder; a flow control valve, which is located between the high pressure connection and the connection of the motor opening and which includes a flow opening, which is arranged to adjust between the fully closed position and the fully open position; and a pressure regulator, which is located between the high-pressure connection and the flow control valve, in which the pressure of the regulator acting at the first connection point between the pressure regulator and the flow control valve acts through the first control channel on the pressure regulator in order to close it. The second control channel, including the first limiter, is configured to transfer the load pressure, which acts in the connection of the motor hole, from the second connection point located between the flow control valve and the connection of the motor hole, through the first limiter to the third connection point, in which a first control pressure, the third connection point being connected to a pressure regulator in order to act on it in the opening direction by said first control -governing pressure, wherein the third connection point is connected to the low-pressure connection via a second limiter adjustment.

Preferred embodiments of the invention are described in the detailed description and in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 depicts a conventional LS valve as described above.

Figure 2 is a conventional LS valve for controlling pressure as described above.

Figure 3 is a diagram of a valve device according to a first embodiment of the invention.

4 is a sectional view of a specific embodiment of a valve device according to a first embodiment of the invention.

5 is a diagram of a specific embodiment, which is shown in figure 4.

6 is a diagram of a valve device according to a second embodiment of the invention.

7 is a cross section of a specific embodiment of a valve device according to a second embodiment of the invention.

Fig. 8 is a diagram of a specific embodiment, which is shown in Fig. 7.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Figure 3 depicts a simplified diagram of a first embodiment of a valve device according to the invention. The valve device 1 includes a high pressure connection P ', which is connected to a pressure source in the form of a pump P, preferably a variable displacement pump. Additionally, the valve device 1 includes a low pressure connection T ', which is connected to a low pressure tank T.

At the other end of the valve device 1, there is a motor hole connection A ′, which is adapted to be connected to the motor hole A on a hydraulic motor M, which in the shown embodiment is shown as a single-acting hydraulic cylinder (see FIG. 4). However, the invention is not limited to the use of single-acting hydraulic cylinders, but, on the contrary, can be preferably used on other types of hydraulic motors, such as, for example, double-acting hydraulic cylinders, shaft-driven motors or the like.

A flow control valve F is located between the high pressure connection P ′ and the motor opening connection A ′ in order to regulate the flow to the motor opening connection A ′. For this purpose, the flow control valve F includes a flow opening, which is arranged to adjust between a fully closed position and a fully open position. The flow through the flow control valve F is proportional to the size of the flow opening, but also depends on the pressure drop across the flow control valve, so the flow depends on the pressure both closer upstream and downstream of the flow control valve F. Preferably, the first bypass valve 2 is positioned closer along the flow control valve F in order to prevent flow in the wrong direction, that is, in the direction opposite to the pump flow. However, alternatively, the bypass valve 20 may be placed in other areas.

A pressure regulator R is located between the high pressure connection P ′ and the flow control valve F in order to regulate the pressure downstream of the flow control valve F, which is indicated by the pressure P _{R of the} regulator and acts at the first connection point 3 located between the pressure regulator R and the valve F flow control. The first control channel 4 is configured to transfer the pressure P _{R of the} regulator to the pressure regulator R and act on it in the closing direction. It is also preferable to use a spring S, which constantly acts on the pressure regulator R in the opening direction.

A second control channel 5, which includes a first stop 6, is located between the flow control valve F and the motor opening connection A '. The second control channel 5 is configured to transfer the pressure P _{L of the} load, which acts in the connection A 'of the motor hole, from the second connection point 7 through the first restrictor 6 to the third connection point 8, in which the first control pressure P _C acts. The first restrictor 6 may preferably be constant and independent of the regulation of the flow control valve F.

The third connection point 8 is also connected to the pressure regulator R and acts on it in the opening direction by the aforementioned first control pressure P _C , and further, the third connection point 8 is connected to the low pressure connection T 'through the second restrictor 9. The second restrictor 9 is preferably made with the possibility of regulation, for example, with the possibility of regulation depending on the valve F of the flow control, and possibly an adjustable second restrictor 9 can be located so that the flow h Res second stopper section 9 is decreased when the flow through the section F regulating valve flow hole to a compound A 'of the motor opening increases.

The third connection point 8 is also connected to a selective valve 10, which also receives control pressure from other valve devices and transfers the control pressure to pump P. Selective valve 10 is in a known manner adapted to transfer the largest of the incoming control pressures to pump P, so that the device which currently requires the highest pressure, regulates the pressure of the pump P.

Preferably, the second stop 9 is positioned so that it is fully open when the flow control valve F is closed or barely open, in which it is closed to a certain position of the flow control valve, so that it forms a stop that gradually decreases as as the flow control valve opens smoothly. Such a function means that when the flow control valve F is open a small amount, the flow further downstream will pass through the first restrictor 6 and the second restrictor 9, and not to the connection of the motor opening A ', unless the pressure in the connection of the motor opening A' very little.

The adjustable second stop 9 may preferably be electrically adjustable. Thus, it is possible to adjust the valve device 1 and its settings without the need to adapt production for each individual valve. This possibility is due to the fact that the properties of the valve device are largely controlled by the characteristics of the second stop 9. Various properties can be adapted to the specific application in which the valve device 1 is to be used, as well as to the specific requirements of a particular operator. Additionally, it is possible with one software to change the properties of an already installed valve device. Therefore, the practicality of the valve device is improved due to the fact that, for example, the valve device can be used in several different areas, and due to the fact that it can be easily adapted to several different specific requirements of various specific operators.

The first embodiment of the valve device 1 according to the diagram in Fig. 3 is shown in longitudinal section in Fig. 4, and Fig. 5 shows an alternative circuit for the same embodiment. 4 and 5, the flow control valve F is part of a valve spool H valve. The valve spool H is arranged to be adjustable between three positions: a first closed position, which is shown in the figures and in which the flow from the high pressure connection P ′ is restrained by the valve spool H, and two open positions. In the first open position, in which the valve spool H has been shifted to the right in FIG. 4 and down in FIG. 5, the flow control valve will open gradually and hydraulic fluid can flow through the first flow hole 18 that is provided on the valve spool H and which is connected both to the outlet pressure of the regulator R and the first point 3 compound to the second compound point 7 from which a stream can flow through the bypass valve 2 as soon as the pressure in the second point of the compound 7 exceeds the pressure P _L HEAT ki, which acts in the compound A 'of the motor opening. The first flow hole 18 mainly corresponds to the flow control valve F in FIG.

Additionally, the second connection point 7 is connected to the third connection point 8 through the first restriction 6. The adjustable second restriction 9 in the embodiment shown in FIG. 4 is formed by a second flow hole 19, the flow through which cross section gradually decreases as the valve The flow control valve F opens through the first flow hole 18 and as the valve spool H moves to the right.

In the shown embodiment, the pressure regulator R has a control valve 11, which is located in the valve body with three separate chambers: the right chamber 12, which is through the control channel 4 is in control connection with the first connection point 3; which makes up the central chamber; and the left chamber 13, in which the spring S is located, which, together with the pressure P _C in the left chamber, acts on the control valve 11 in the opening direction, that is, to the right in Fig. 4.

The difference from the circuit in FIG. 3 is that FIGS. 4 and 5 show how the cylinder chamber is emptied through the hole A of the motor. When the valve spool is adjusted to the second open position, that is, to the left in FIG. 4 and up in FIG. 5, the outlet recesses 14 connect the motor opening connection A ′ to the low pressure connection T ′. The more the valve spool H is biased to the second open position, the larger the opening for flow through the outlet cavities 14 becomes.

To the left of the valve spool H in FIG. 4 is a double-acting spring structure 15 that holds the valve spool H in the closed center position shown in FIG. 4.

6-8, an alternative valve device according to the invention is shown accordingly, as the first valve device was shown in FIGS. 3-5. An alternative valve device differs from the first embodiment of the valve device only in two features, and mainly these features will be discussed above.

The first difference is that the third control channel 16, including the third restrictor 17, is configured to transfer the pressure of the regulator P _R , which acts at the first connection point 3 between the pressure regulator R and the flow control valve F, to the third connection point 8 .

The second difference is that the second bypass valve 20 is located in the second control channel 5 in order to prevent the flow from the outlet of the flow control valve F to the third connection point 8 through the second connection point 7. Therefore, the second bypass valve 20 opens to the second connection point 7 and transfers the flow simultaneously with the flow control valve F when the control pressure P _C at the third connection point 8 exceeds the load pressure P _L at the second connection point 7.

This gives advantages in systems with high inertia, for example, in cases where it is necessary to move the swing arm or boom of the crane. When the flow control valve F is opened in order to let the flow in, in a conventional valve device, it will first require very high pressure to overcome the inertia of the crane boom and move it. However, as the crane's boom picks up speed, the necessary pressure will decrease. However, the control pressure that is transferred to the pump in the traditional system will remain elevated due to the fact that the flow that the pump delivers is much greater than the cylinder chamber can receive. Consequently, the flow corresponding to the loss of energy will enter the tank under very high pressure. In the invention according to the second embodiment, the flow will instead flow from the first connection point 3, through the third and second connection points 8 and 7, respectively, into the connection A 'of the motor opening, as a result with very small pressure losses. At the same time, a lower pressure P _C will be transferred to the pressure regulator R and the pump P, which, therefore, can operate at a lower pressure value.

7 shows an alternative embodiment of the valve device 1, in which the third control channel 16 consists of a through hole that connects the first connection point 3 to the third connection point 8. In the center of the third control channel 16, a connection is made to the second control channel 6, which includes a second bypass valve 20, which opens to the second connection point 7. Therefore, there is a difference from the circuit of FIG. 6, but with respect to strict functionality, there is no difference.

The connection point 8, which is shown in FIG. 6 as a point, in FIG. 7, can be considered as an formed part of the third control channel 16, which is located further along the third stop 17 and connected to the first stop 6. In general, the diagrams shown are simplifications that show only those parts that are important for the invention and, most importantly, the connection points are theoretical points that in practice can be formed by a part of the channel or the like.

Fig. 8 shows a second circuit of an alternative valve device 1. Therefore, this circuit differs from the circuit shown in Fig. 5 in the same way that Figs. 7 and 4, i.e., a third control channel 16, which includes a third the stopper 17 and the second bypass valve 20. The third control channel 16 is not shown in the second open position when the valve spool has been shifted up, because in this position it does not function.

Claims (7)

1. A hydraulic valve device (1), including:
high pressure connection (P ') and low pressure connection (T');
at least one connection (A ') of the motor hole, which is configured to connect to the hole (A) of the motor on a hydraulic motor (M), preferably a hydraulic cylinder;
a flow control valve (F), which is located between the high pressure connection (P ') and the motor opening (A') and which includes a flow hole (18) that can be adjusted between the fully closed position and the fully open position ;
a pressure regulator (R), which is located between the high pressure connection (P ') and the flow control valve (F), in which the pressure regulator (P _R ) acting at the first point (3) of the connection between the pressure regulator (R) and the valve ( F) flow control, through the first control channel (4) acts on the pressure regulator (R) to lock it, characterized in that it contains a second control channel (5), including the first restrictor (6) and configured to transfer pressure ( P _L ) the load that acts in the connection (A ') the motor port, from the second connection point (7) located between the flow control valve (F) and the motor opening connection (A '), through the first stop (6) to the third connection point (8) at which the first control pressure (P _C ), the third connection point (8) being connected to the pressure regulator (R) with the possibility of acting on it in the opening direction by the first control pressure (P _C ), the third connection point (8) being connected to the low pressure connection (T ') through an adjustable second stop (9). 2. The device (1) according to claim 1, characterized in that the third control channel (16), including the third restrictor (17), is designed to transfer pressure (P _R ) of the controller acting at the first point (3) of the connection between a pressure regulator (R) and a flow control valve (F), through a third stop (17) to said third connection point (8). 3. The device (1) according to claim 2, characterized in that the bypass valve (20) is located between the second connection point (7) and the third connection point (8) and is configured to open to the second connection point (7), for transfer flow simultaneously with the flow control valve (F) when the control pressure (P _C ) at the third connection point (8) exceeds the load pressure (P _L ) at the second connection point (7). 4. Device (1) according to any one of the preceding paragraphs, characterized in that the adjustable second restrictor (9) is regulated depending on the valve (F) regulating flow. 5. The device (1) according to claim 4, characterized in that the adjustable second restrictor (9) is adjusted so that the flow through the cross-section of the restrictor (9) decreases when the flow through the cross-section of the valve opening (F) of the flow to the connection (A ' ) motor holes increase. 6. The device (1) according to claim 1, characterized in that the adjustable second limiter (9) is made with the possibility of electrical regulation. 7. The device (1) according to claim 1, characterized in that the spring (S) is configured to continuously act on the pressure regulator (R) to unlock it.

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